Lubricant



Patented June 13, 1944 LUBRICAN'E John D. Morgan, South Grange, N. 3.,aasignor to Cities Service Oil Compmy, New York, N. E... a corporationof Pennsylvania No Drawing. Application July it, 1942, Serial No. @32198 Claims.

This invention relates to lubrication. More specifically the inventionrelates to low temperature lubrication.

For those machines, such as the aeroplane, truck, automobile and cannon,which must operate under a wide range of temperature conditions, it isimportant that the viscosity of the lubricants being used shall be quiteuniform throughout the entire temperature range of operations. It isalso important that the lubricants used shall not be corrosive or easilyoxidizable or susceptible of being decomposed under the conditions ofoperation.

The primary object of the present invention is to provide a method oflubrication and the lubricant therefor which will be efiective forlubrication over the entire temperature range in which it may be calledupon to operate.

Another object of the invention is to provide a lubricant that isnon-corrosive on the commonly used bearing metals.

A further object of the invention is to provide a lubricant that isstable and not readily decomposed and which has high load-carryingcapacities.

With these and other objects inview the invention consists in theimproved method of lubrication and the lubricant therefore hereinafterdescribed and particularly defined in the claims.

I have discovered that the organic esters of benzoic acid have goodlubricating qualities. For

" example the alkyl benzoates are generally colorless liquids, benzylbenzoate is a colorless liquid, and all of these esters have lubricatingqualities or load-carrying capacities approximately equal to theload-carrying capacities of a Pennsylvania grade spindle oil having aviscosity of 100 at 100 F.

The physical properties of the benzoic acid esters are well adapted forlubrication over a temperature range of 200 F. down to 50 F. The esterswhich have been tested, furthermore, are non-corrosive to the usualbearing metals and alloysand are not decomposed at the high temperatureor at the low temperature, or under the strain of extreme pressurelubrication.

The physical properties of some of the benzoic acid esters are asfollows:

The viscosities of some of these esters have been determined as follows:

It will be seen that the above viscosities of these benzoate esters arecomparatively uniform over a wide temperature range. Furthermore theesters have high boiling points and most of them have good viscositiesat a temperature of 40 F. The ethyl, amyl and benzyl benzoates all haveload-carrying capacities for lubrication which are better than theordinary Pennsylvania grade spindle oil. Furthermore, with all of thebenzoate esters if approximately 1% of one of the commonly used extremepressure addition agents is used, it will impart to the esters aload-carrying capacity suitable for extreme pressure lubrication. Withthe e-ball testing machine for extreme pressure loading it has beenfound that the benzoates will tend to develop a friction when loads of250, to 600 lbs. have been placed on the bearings. With the 1% additionof an extreme pressure additive allof these benzoates will op eratewithout showing a tendency to develop friction for load-carryingcapacities above 1000 lbs., which is the upper measuring, limit of the4- ball testing machine.

The addition agents which are soluble in the benzoates and which giveeffective load-carrying phite, or a mixture of tricresyl phosphite andtricresyl phosphate which is described in the patent to Engelke No.2,260,303 granted October 28th, 1941. Polane, which is a commercialproduct, is manufactured by the Patent Chemicals Company and isunderstood to be an ester of a fatty acid or chlorinated ester of afatty acid, such as ethyl laurate or chlormethyl stearate. Santolube#261 which is an addition agent, is manufactured and sold by theMonsanto Chemical Company. This product is described as a metallicderivative of an alkylated carboxylic acid containing compounds of tinand sulfur.

The benzoates may be used as the base lubricant for the manufacture ofgreases. Methyl .benzoate is soluble in or compatible with lithiumcompatible with a mixture of sodium and aluminum stearates. It ispreferred to use about 1% or one oi the additives mentioned above in thebenzoates when' they are blended with the soaps. The lithium soaps mayvary from 3 to esters such as tributyl phosphate, ethyl oxalate,

ethyl lactate, dibutyl phthalateand; the like, for the purpose orobtaining alubricantwhich' has any desired viscosity curve andboiling,point. Hydraulic fluids which are used for brake operation orgun recoil fluids require specific physical characteristics among-whichare viscosityand oiliness. The benzoates may be blended with, or aremutually soluble in, the above mentioned esters and :provide the desiredphysical characteristics for hydraulic fluids. 1

The preferred form 01' the invention having been thus described, what isclaimed as new is: 1. A lubricant comprising a major portion oi an alkylbenzoate as a base lubricant and a small amount of-a lithium soapblended therewith to producea stable grease.

assmso 2. A lubricant comprising a major portion oi benzylibenzoate as abase lubricant and a small amount of a lithium soap blended therewith toproduce a stable grease.

3. A lubricant comprising a major portion of an ester of benzoic acid asa base lubricant and having a small amount of a lithium soap blendedtherewith to produce a stable grease.

4. A lubricant comprising an ester of benzoic acid 85% to 95% blendedwith a lithium soap 5. A lubricant comprising an ester of benzoic acid93%, lithium soap 6%, extreme pressure additive 1%.

. ate.

8. A lubricant comprising an ester of benzoic acid 92%, lithium soap 6%,aluminum soap 1%, extreme pressure additive 1%.

JOHN D. MORGAN.

